Hey Zpost, DKF wanted me to let you know that this exhaust project is still very much alive. DKF ran into some speedbumps that they are in the process of ironing out.

A new time line for the group buy will be introduced once everything is worked out.

If there is a Z4 M in the phoenix area with open flow headers that is willing to do some testing, send me a PM.

Thanks,
Chris

DKF Exhaust System Testing:

I have gone through many parts on this car in pursuit of fine tuning what suits my build. This is fun & the knowledge gained is rewarding, but that knowledge does not come cheap and money is lost in the process. I am excited about this unique opportunity; In exchange for posting my findings, DKF has given me the ability to "try before I buy." This is perfect, I love working on my M coupe and I only have to pay for what I keep

Here is the breakdown of my game plan for the components I am testing.

At a minimum, I will be working on and posting the following data as I go through this DKF exhaust journey:
-Product info
-Dynos'
-Weight Comparisons’
-HD videos
-DB level testing
-DIY for install
-SC tune findings
-Group buy interest and group buy pricing

Product Info:
Product info will include photos and descriptions of each of the components tested

Dynos':
All Dyno's will be performed @ Good Speed Performance Labs. Good Speed is ESS approved for the installation of all ESS tuning products and performed the installations on my VT-1 S/C kit. In addition, Jon at Good Speed played a key role in the development of both the VT-1 and VT-2 kits for our cars working side by side with ESS tuning throughout the process. Jon is single handedly responsible for bringing us a true CAI for our VT kits. All this to say the car will be in good hands and the data will be precise.

All Dynos' performed on my car will be with the VT-1 S/C kit and the OEM European headers (cat less )

All Dynos' will be performed on 91 octane from Costco

I will attempt to perform all Dynos' during similar ambient temperatures
My First Dyno will be Saturday 11/19/11this will be the baseline dyno.
For this dyno I have removed the DKF system and re-installed the OEM S-pipe, X-pipe and mufflers.

The plan following this dyno will be to perform one dyno per week throughout the project.

Weight Comparisons:
Each component I have in my possession will be weighted on a certified & calibrated shipping scale

Photos of each component on the shipping scale will be posted

HD Videos

HD camera model and settings will be posted. Dio and I will be using the same camera and settings for consistency

Videos of several system variations will be posted

Sound DB testing

DB testing will be performed for the systems tested. Results will be posted side by side for compassion

DIY for Install
This will take a great deal of time to complete, but will be finished before the group buy is completed.

The format of the DIY will be like the Exhaust and Splitter DIY done previously

S/C tune findings
As some have expressed concerns about tunes adapting to the DKF s exhaust systems, finding will be posted as testing is completed

Group Buy Pricing & Group Buy Interest

Already working on establishing group buy pricing with DKF, once they release their GB pricing we can start an interested list.

This post will include an overview of each component. The post will be updated regularly. Each time information is updated a corresponding post will be added the end of thread letting everyone know and update has been made. For more in-depth information on the research that went into the system, see the attached link:http://www.zpost.com/forums/showthread.php?t=419023

The Basic Idea:
All of the combinations of DKF components will make similar power (+/- 5%). Then why the abundance of options you ask? (This is the first question I asked)
The answer is simple…SOUND
There is one thing we can all agree on when it comes to exhaust upgrades… maximum performance.
Then there is one thing that almost no one agrees with when it comes to exhaust upgrades… sound.
This is where I believe DKF may have outdone themselves. There are going to be several different resonators, catalytic converters, race pipes and mufflers offered. In the end we should be able to fine tune and find the exact exhaust note we are looking for. For me it will probably be somewhere on the raw motorsport end of the spectrum.

Side by Side DKF/OEM:

Finish:All components have been Jet Hot ceramic coated. Although the finish looks great, the purpose of the ceramic coating goes far beyond appearance.
Short version: The DKF system increased the diameter of the exhaust system to allow for a greater volume of gas to escape. The increased diameter of the exhaust tubing slows the velocity of the exhaust gases; the ceramic coating brings the velocity of the exhaust gases back up to speed. End result; Greater flow and balanced velocity.

Hardware:

With the DKF “Header Back” exhaust system, the connection between the headers and the S-pipe is the only OEM style hardware found. The remaining six connection points utilize racing flanges and racing clamps to optimize flow and limit turbulence.

Hangers:

-For anyone who has installed exhaust on our cars and worked hard to get the perfect tip alignment, DKF has created a serious solution for this. The hangers allow left to right and up and down adjustment independent of one another. This is a huge improvement when compared to the spherical joint that BWM uses where all alignment relies on the spherical joint and a two bolt flange.

-The hangers have also been designed to dampen and help eliminate drone by using an isolation pad between the hangers and body, isolation mounts between the mufflers and the hangers and isolation washers

-Stainless steel laser welded construction for sereious strength

In a word AWESOME!

Section 1 components:S-Pipe:
The stepped S-pipe is one of two components that make up the “section 1” in the DKF system. The S-pipe is a stepped from 2.25” to 2.50” because of the exhaust valve port size and the timing of the exhaust pulse. In short, the purpose is to carry the highest velocity possible before the next diameter change.

(the following resonators and straight pipes are options to complete the “section 1” more options will be added as the post is updated)

X-Pipe:
The x-pipe is one of three components that make up the “section 2” in the DKF system. DKF designed the X-pipe with minimal bends and minimized bend angles to pull off the least amount of restriction. The thing that surprised about the X-pipe is the fact that you can see straight through it from one end to other.

(the following mufflers are options given to complete “section 2” more options will be added as the post is updated)

Street:
-The lowest volume option offering better performance than stock, but less than the Sport and Race options
-Work in progress @ DKF, pics will follow

This post will be updated regularly until all weight comparisons are made. See attached photos for the weight of each DKF component currently in my possession. Once removed from the car, weights for the OEM system will be added. I will add a spreadsheet to more clearly show the differences between individual components and complete systems. For the time being, check out the photos bellow.

Update: post #2, Product info has been updated 24 photos and descriptions of the compenents in hand. Racing cats and new hangers should arrive the 22nd, so more to come soon

Quote:

Originally Posted by Blind32

Soon to be another awesome thread by crfine88!

thank you sir

Quote:

Originally Posted by VinnieAces

subscribed

Quote:

Originally Posted by vortex_tuning

Can't wait to see updates!

I will keep them coming

Quote:

Originally Posted by Beedub

Dont forget to take some nice HD shots of the rear end end on the dyno... the race and catless option will be a flamefest on your Supercharged car once it gets warmed up ;-)

Good call, I should have Goodspeed doy the dyno run for me when it is dark out

Quote:

Originally Posted by Jumbosock

By the way... not to get off topic too much but I'm shocked you use Costco gas.

This is by Goodspeeds recommendation. The Costco in Scottsdale is a block away from the shop. According to Jon @ Goodspeed, this particular Costco goes through so much 91 octane that the tanks stay clean and the fuel is never old. It is sort of a pain to fuel up there because the lines are ridiculous every day. Until this recommendation, I have always been a top tier fuel guy too.

Quote:

Originally Posted by flipm3

Now this is how you write a thorough product review.

I am looking forward to seeing all your results and impressions even though I don't own an Z4, haha.

Thank you, I will keep the udate coming

Quote:

Originally Posted by Diokaef

The hangers work for sure in your car

Can't wait to try the new hanger design

Quote:

Originally Posted by gatorfast

How come? 91 octane is 91 octane. I've used many different brands including the so called top tier and never noticed any sort of difference.

91 because it is the highest octane pump gas I can get in AZ. Lower octane fuel directly affects our cars HP output; low octane will cause higher intake temps/detonation resulting in timing corrections to protect the engine and diminish HP.